Tubular TYK Weld Joints: Fabrication and Inspection

Introduction: inspection problems are encountered during the construction of round tubular members, especially at the TKY node connections. Often these are not primary load carrying structures or they have limited structural function. Nevertheless, in the offshore industry, tubular TKY construction is used as the primary load path for structures such as fixed offshore platforms. The jacket of an offshore structure is made-up of tubular members. These tubular members are made-up of steel and designed to resist yield and buckling loads. The tubular sections form various types of joints like T joint, K joint, Y joint. In addition to the weight of the structure and equipment. These joints are subjected to operational and extreme cyclic loading conditions resulting from normal wind and wave action earthquakes. Hurricanes. Vibrating equipment? Extreme cold. Due to which fatigue failure starts and increases as the time passes. Loads are therefore either static or cyclic, and the quality of the structural Weld for tubular connections must endure for the design life of the structure. Worldwide, various code standards and recommended practices are used for design, fabrication, welding and inspection of TKY joints such as #AWS #D1.1, #iso 19902, #api RP2 and #DNV RP C203. Even a cursory review of the code requirements for #tubular #welding and #inspection reveals that tubular node connections are more complex than flat plate structural fabrication. Thorough planning and training for all phases of a structural tubular fabrication project will help to avoid unnecessary problems and therefore maximize production and minimize rework and repair. This presentation focuses on the fit up and welding visual inspection of tubular TTY joints, with the objective of emphasizing the need for planning. Overview of Concept Related to T, K, Y Joint Configuration: Imagine two box hollow sections intersecting at a 90-degrees angle, as shown in the picture. If both sections are the same size, the local angle at the sides indicated by the arrows will be 90 degrees, while the other two sides will have a local angle of 180 degrees. It's important to note that even though the overall intersection angle is 90 degrees, the local angle at the weld configuration changes based on the specific location. Similarly, let's explore some additional examples. By examining these examples, it becomes clear that the distribution of acting stresses is influenced by the local angle, regardless of the overall intersecting angle of the brace or structural member. For instance, even if sections intersect at 90 degrees, stress concentration will differ between the localized areas with 90-degree and 180-degree angles. Now, consider replacing the box sections with circular tubular sections. Since intersecting sections are circular, the bevel angle and local dihedral angle will vary along the weld line in relation to the local angle formed between the chord and brace. Fabrication and Explanation of the Fundamentals of TKY weld Joints: Here we have the Pipe Tubular, which needs to be cut to specific dimensions required to create brace angle according to the construction drawing. Here's an actual picture of a node brace stub. As you can see in the plan view of the cut section, it has an oval shape appearance. When this stub is connected to the chord (another tubular member), the resulting node connection can be divided into three key areas. 1) Heel: This refers to the area where the stub connects to the main structure and formed Brace angle providing support and stability. 2) Sides/Saddles: These are the portions of the node connection that surround the stub and help distribute the load evenly. Typically, these are the curved sections on either side of the heel. 3) Toe: The toe is the end section of the node connection, where the stub tapers off. This is the point at the opposite end of the heel area. By understanding these three major areas, we can ensure proper fabrication and installation of the node brace stub, resulting in a strong and reliable connection Extract of AWS D.1.1 denoting different part of Tubular #Node #structure Local #Dihedral Angle Ψ : At the top left, the definition of Dihedral is provided. To better understand it, let's break down the definition. Let's focus on the underlined text and illustrate it on the Node Tubular connection figure.
The underlined text states: The angle measured in a plane perpendicular to the line of the weld. The white line represents the line of the weld. Now, let's read the blue and yellow highlighted text together, which states: "A plane perpendicular to the line of the weld." To better understand it, points are marked at various locations on the weld line. By placing a set square with a right angle on the weld line, aligning the base of the square with the weld line, we can then draw a perpendicular to the weld line. At the centerline of the heel area, the dihedral angle (Ψ) is equal to the brace angle (Ꝋ).

[shezwanm]

You've done an exceptional job! Your dedication and effort really shine through in your work. Keep up the fantastic work!

[baranidharan]

Wow, this is gold Nadeem bhai!!! It's so hard to find good info on TKY weld joints even in google and you absolutely nailed it. It is a complex subject and explaining them clearly takes real expertise . I can't believe you were willing to share this knowledge - this is a game-changer for people in our field. Thanks a ton!